Asset Retirement Obligations (Cumulative Decommissioning And Retirement Cost Liabilities And Expenses) (Details) - USD ($) $ in Millions	1 Months Ended			8 Months Ended	12 Months Ended
	Dec. 31, 2019	Aug. 31, 2019	Jan. 31, 2019	Aug. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	$ 6,159.2				$ 6,159.2	$ 6,923.4	$ 6,185.8
Accretion					414.0	423.5
Change in Cash Flow Estimate					273.7	505.4
Spending				$ (1,406.3)	(45.6)	(191.3)
Entergy Arkansas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	1,242.6				1,242.6	1,048.4	981.2
Accretion					68.0	60.4
Change in Cash Flow Estimate					126.2	8.9
Spending					0.0	(2.1)
Entergy Louisiana [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	1,497.3				1,497.3	1,280.3	1,140.5
Accretion					69.5	63.2
Change in Cash Flow Estimate					147.5	85.4
Spending					0.0	(8.8)
Entergy Mississippi [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	9.7				9.7	9.2	9.2
Accretion					0.5	0.5
Change in Cash Flow Estimate					0.0	0.5
Spending					0.0	(1.0)
Entergy New Orleans [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	3.5				3.5	3.3	3.1
Accretion					0.2	0.2
Change in Cash Flow Estimate					0.0	0.0
Spending					0.0	0.0
Entergy Texas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	7.6				7.6	7.2	6.8
Accretion					0.4	0.4
Change in Cash Flow Estimate					0.0	0.0
Spending					0.0	0.0
System Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	931.7				931.7	896.0	861.7
Accretion					35.7	34.3
Change in Cash Flow Estimate					0.0	0.0
Spending					0.0	0.0
Entergy Wholesale Commodities [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	0.5				0.5	0.4	0.3
Accretion					0.1	0.0
Change in Cash Flow Estimate					0.0	0.1
Spending					0.0	0.0
Big Rock Point [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	40.3				40.3	39.7	38.9
Accretion					3.2	3.2
Change in Cash Flow Estimate					0.0	0.0
Spending	0.0				(2.6)	(2.4)
Indian Point 1 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	238.6				238.6	227.9	217.6
Accretion					19.5	18.6
Change in Cash Flow Estimate					0.0	0.0
Spending	0.0				(8.8)	(8.3)
Indian Point 2 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	829.0				829.0	768.0	708.7
Accretion					65.5	60.6
Change in Cash Flow Estimate					0.0	0.0
Spending	0.0				(4.5)	(1.3)
Indian Point 3 [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	808.4				808.4	750.6	694.5
Accretion					62.5	58.0
Change in Cash Flow Estimate					0.0	0.0
Spending	0.0				(4.7)	(1.9)
Palisades [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	549.8				549.8	508.0	470.4
Accretion					42.9	39.6
Change in Cash Flow Estimate					0.0	0.0
Spending	0.0				(1.1)	(2.0)
Pilgrim [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	0.0				0.0	816.5	651.4
Accretion					44.1	58.6
Change in Cash Flow Estimate					0.0	117.5
Spending		$ (836.7)			(23.9)	(11.0)
Vermont Yankee [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation	$ 0.0				0.0	567.9	$ 401.5
Accretion					1.7	25.9
Change in Cash Flow Estimate					0.0	293.0
Spending			$ (569.6)		$ 0.0	$ (152.5)